Hold bit and UA response.

Kevin D Butt kdbutt at us.ibm.com
Tue May 17 14:55:40 PDT 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* Kevin D Butt <kdbutt at us.ibm.com>
*
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If we are to believe what we have been hearing lately, a lot of
applications don't even see the UA's as the device drivers swallow them.
I don't know, but it seems abnormal for a UA to be returned to the I_T
Nexus that caused it by a command. 

Thanks, 

Kevin D. Butt
Fibre Channel & SCSI Architect, IBM Tape Firmware, 
6TYA, 9000 S. Rita Rd., Tucson, AZ  85744
Tie-line 321; Office: 520-799-5280, Lab: 799-5751, Fax: 799-4138, Email:
kdbutt at us.ibm.com 



Paul.A.Suhler at certance.com 


05/17/2005 02:26 PM 

To
Kevin D Butt/Tucson/IBM at IBMUS 

cc
owner-t10 at t10.org, t10 at t10.org 

Subject
Re: Hold bit and UA response.

	






Hi, Kevin.

I don't recall any discussion on the point when this first went into
SSC.
I'm unable to construct a scenario where the application client that
issued
the command needs the unit attention.  (I can see that it would be
useful
if the HOLD bit were not set and IMMED was.  Then the application client
could poll until it sees the UA, then start talking to the MAM before
threading, etc. is finished.  *If* the device actually allowed that,
which
isn't a given.)

The issue is now whether there would be any application clients that
would
be broken by *not* getting the UA, were the change to be made.

Thanks,

Paul
++++++++++++++
Paul Suhler
Firmware Engineer
Quantum Corporation
1650 Sunflower Avenue
Costa Mesa, California  92626
(714) 641-2485 (voice)
(714) 966-7328 (fax)



 

                     "Kevin D Butt"

                     <kdbutt at us.ibm.co        To:       t10 at t10.org

                     m>                       cc:

                     Sent by:                 Subject:  Hold bit and UA
response.                                                     
                     owner-t10 at t10.org

 

 

                     05/17/2005 12:03

                     PM

 

 






In SSC-3r01c under the Load/Unload command, Clause 7.2 pg 76 there is
this
description of the HOLD bit.

A LOAD bit of one and a HOLD bit of one specifies if the medium has not
been moved into the logical unit, the
medium shall be moved in but not positioned for access. The EOT and
RETEN
bits shall be set to zero. Following
successful completion, the device server shall return GOOD status. If
both
the medium and device server support
MAM, the device server shall generate a unit attention condition for all
initiators and the additional sense code shall
be set to MEDIUM AUXILIARY MEMORY ACCESSIBLE.

My question is if the intent is that the UA be generated for "all
initiators" as is stated, or if the intent is to generate the UA for
"all
other I_T Nexuses"?

Thanks,

Kevin D. Butt
Fibre Channel & SCSI Architect, IBM Tape Firmware,
6TYA, 9000 S. Rita Rd., Tucson, AZ  85744
Tie-line 321; Office: 520-799-5280, Lab: 799-5751, Fax: 799-4138, Email:
kdbutt at us.ibm.com








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<br><font size=2 face="sans-serif">If we are to believe what we have been
hearing lately, a lot of applications don't even see the UA's as the device
drivers swallow them. &nbsp;I don't know, but it seems abnormal for a UA
to be returned to the I_T Nexus that caused it by a command.</font>
<br>
<br><font size=2 face="sans-serif">Thanks,</font>
<br><font size=2 face="sans-serif"><br>
Kevin D. Butt<br>
Fibre Channel &amp; SCSI Architect, IBM Tape Firmware, <br>
6TYA, 9000 S. Rita Rd., Tucson, AZ &nbsp;85744<br>
Tie-line 321; Office: 520-799-5280, Lab: 799-5751, Fax: 799-4138, Email:
kdbutt at us.ibm.com</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td width=40%><font size=1 face="sans-serif"><b>Paul.A.Suhler at certance.com</b>
</font>
<p><font size=1 face="sans-serif">05/17/2005 02:26 PM</font>
<td width=59%>
<table width=100%>
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<td>
<div align=right><font size=1 face="sans-serif">To</font></div>
<td valign=top><font size=1 face="sans-serif">Kevin D Butt/Tucson/IBM at IBMUS</font>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td valign=top><font size=1 face="sans-serif">owner-t10 at t10.org, t10 at t10.org</font>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td valign=top><font size=1 face="sans-serif">Re: Hold bit and UA response.</font></table>
<br>
<table>
<tr valign=top>
<td>
<td></table>
<br></table>
<br>
<br>
<br><font size=2><tt><br>
Hi, Kevin.<br>
<br>
I don't recall any discussion on the point when this first went into SSC.<br>
I'm unable to construct a scenario where the application client that issued<br>
the command needs the unit attention. &nbsp;(I can see that it would be
useful<br>
if the HOLD bit were not set and IMMED was. &nbsp;Then the application
client<br>
could poll until it sees the UA, then start talking to the MAM before<br>
threading, etc. is finished. &nbsp;*If* the device actually allowed that,
which<br>
isn't a given.)<br>
<br>
The issue is now whether there would be any application clients that would<br>
be broken by *not* getting the UA, were the change to be made.<br>
<br>
Thanks,<br>
<br>
Paul<br>
++++++++++++++<br>
Paul Suhler<br>
Firmware Engineer<br>
Quantum Corporation<br>
1650 Sunflower Avenue<br>
Costa Mesa, California &nbsp;92626<br>
(714) 641-2485 (voice)<br>
(714) 966-7328 (fax)<br>
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<br>
In SSC-3r01c under the Load/Unload command, Clause 7.2 pg 76 there is this<br>
description of the HOLD bit.<br>
<br>
A LOAD bit of one and a HOLD bit of one specifies if the medium has not<br>
been moved into the logical unit, the<br>
medium shall be moved in but not positioned for access. The EOT and RETEN<br>
bits shall be set to zero. Following<br>
successful completion, the device server shall return GOOD status. If both<br>
the medium and device server support<br>
MAM, the device server shall generate a unit attention condition for all<br>
initiators and the additional sense code shall<br>
be set to MEDIUM AUXILIARY MEMORY ACCESSIBLE.<br>
<br>
My question is if the intent is that the UA be generated for "all<br>
initiators" as is stated, or if the intent is to generate the UA for
"all<br>
other I_T Nexuses"?<br>
<br>
Thanks,<br>
<br>
Kevin D. Butt<br>
Fibre Channel &amp; SCSI Architect, IBM Tape Firmware,<br>
6TYA, 9000 S. Rita Rd., Tucson, AZ &nbsp;85744<br>
Tie-line 321; Office: 520-799-5280, Lab: 799-5751, Fax: 799-4138, Email:<br>
kdbutt at us.ibm.com<br>
<br>
<br>
<br>
<br>
<br>
</tt></font>
<br>
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